Vibrator with hydraulically controlled eccentricity



Oct. 23, 1962 F. CLYNCH ETAL 3,059,483

VIBRATOR WITH HYDRAULICALLY CONTROLLED ECCENTRICITY Filed May 31, 1960 INVENTORS GEORGE J HANGG/ FRANK CLYNCH 3,059,483 VIBRATOR WITH HYDRAUHCALLY CQNTROLLED ECCENTRICHY Frank Clynch and George J. Hanggi, Ponca City, Okla, assignors to Continental Oil Company, Ponca City, Okla, a corporation of Delaware Filed May 31, 1960, Ser. No. 32,630 1 Claim. (Cl. 74-61) The present invention deals with an improvement in a variable frequency and variable force mechanical vibrator of the type which has a mass or spring biased piston positioned with respect to the rotational axis of the vibrator by hydraulic pressure.

A mechanical vibrator which can be accurately controlled not only in the frequency generated but also in the centrifugal force applied to the object being vibrated has wide usage in the field of earth compaction, vibration generation for structure testing, and seismic wave generation. The vibrator generally has its frequency controlled by a variable speed drive inserted between a constant speed motor and the drive shaft of the vibrator and has its centrifugal force varied by a mass which can be moved closer or farther away from the axis of the vibrator shaft.

One important method for controlling the variation in centrifugal force of a vibrator is to apply hydraulic pressure to a spring biased piston confined in a cylindrical chamber. The cylindrical chamber is mounted transverse to the vibrator shaft. When hydraulic pressure is applied between the end of the cylinder and the head of the spring biased piston mounted therein, the piston will be forced closer to the vibrator axis. Since centrifugal force is a function of the mass times the distance of the mass from the center of the axis and also proportional to the square of the rotation of the shaft, it is obvious that if the rotation of the shaft is to be varied the centrifugal force will likewise vary. It is, however, often times extremely necessary that the centrifugal force remains constant regardless of the rotational speed of the shaft. For example, in order to maintain a constant centrifugal force as the shaft speed is increased, more hydraulic pressure must be applied to the piston to force it nearer to the axis of the vibrator drive shaft. However, hydraulically controlled vibrators in the past have been beset with the problem of applying the hydraulic control fluid to a rotating mass. Since both the shaft and cylinder housing are rotating, a rotatable hydraulic joint was necessary which not only was required to withstand an extremely high hydraulic pressure but also was required to maintain the pressure for an extended period of time during which time the shaft was rotated at an extremely high speed. Rotational hydraulic joints have never proved entirely satisfactory. This is especially true where the joint must rotate at an extremely high speed.

Therefore, it is an object of this invention to provide a hydraulically controlled centrifugal force vibrator which can rotate at unlimited speeds without being limited by a rotational hydraulic joint.

It is a further object of this invention to provide a high speed mechanical vibrator which has an infinitely variable centrifugal force between minimum and maximum limits.

This invention features a mechanical vibrator which has a variable centrifugal force which comprises a shaft having a piston confining chamber mounted transverse thereto, one end of said shaft having a hydraulic reservoir confined therein, a communicating means connected between the hydraulic reservoir and the upper end of said piston confining cylinder, a plunger slideably mounted Patented 0st. 23, 1962 in said hydraulic reservoir, an operating shaft rotatably mounted axially in one end of said plunger such that when the shaft of the vibrator is rotated the plunger will rotate about a fitted operating rod mounted therein such that in or out operation of the operating rod will cause the piston to correspondingly force hydraulic fluid into or out of said piston confining cylinder, thereby moving said spring biased piston closer to or farther away from the axis of said vibrator shaft; the spring biasing means as provided between the opposite face of said piston urges the piston at all times against the hydraulic fluid.

Further objects, features, and advantages of the invention will become apparent from the following description and claim when read in view of the accompanying drawings, in which;

FIG. 1 is a three dimensional, sectional view of the vibrator;

FIG. 2 is a three dimensional view of opposite rotating weights; and

FIG. 3 is a cross-sectional view of the vibrator.

Similar numbers will be used throughout all figures where common structural elements are shown.

Referring to the drawings and particularly to FIGS. 1 and 3, a shaft 10 is rotationally supported by a plurality of bearings 11. Bearings 11 are rigidly mounted in a housing of any suitable type (not shown). A piston 12 is confined within a cylinder 13. Cylinder 13 is rigidly attached transversely to shaft 10, and is closed at the top by any suitable means, such as head 16 which is shown threadedly attached to cylinder 13. An 0 ring 17 is provided to prevent hydraulic fluid from escaping around head 16. A second means such as O ring 18 is used to provide a hydraulic pressure seal for piston 12. It is to be understood that other suitable means known to those skilled in the art may be used for preventing hydraulic liquid from escaping from around the head of piston 12. Axially mounted between bottom 14- and piston 12 is a biasing spring 15. A vent hole 30 provides an escape for air or hydraulic fluid from the lower portion of cylinder 13 below piston 12.

A hydraulic fluid reservoir 21) is provided in shaft portion 10a. A plunger 21 is rigidly inserted within hydraulic fluid reservoir 20 and is likewise provided with a suitable pressure confining means such as O ring 22. A communicating means such as a channel 23 is provided between hydraulic fluid reservoir 20 and the area above piston 12. Plunger 21 is axially moved in hydraulic fluid reservoir 20 by a control rod 25. A suitable housing 26 for control rod 25 is provided to form a protective sheath and a friction hold for the control rod. The end of control rod 25 is provided with a suitable means such as a knob 27 for actuating the control rod. Control rod 25 is rotatably attached to plunger 21 by means of a plurality of bearings 31 which may be of the ball bearing type, as shown, or other suitable types such as sleeve bearings. The bearings must however be adapted to permit longitudinal movement of control rod 25 as well as providing reduced rotational friction. Any suitable means may be employed such as 0 clip 24 to retain the bearings within the plunger 21.

In operation, shaft 10 is rotated at any desired speed. The shaft may be best rotated by a variable speed drive and a constant speed motor or by a variable speed motor (not shown). Rotation of shaft 10 will cause rotation of the entire mass comprising cylinder 13, piston 12, spring 15, and any hydraulic fluid between the upper portion of piston 12 and head 16. The centrifugal force of the rotating mass will be determined primarily by the location of piston 12 and the hydraulic fluid in the cylinder .13. If the centrifugal force is desired to be reduced, knob 27 is pressed causing control rod 25 to force plunger 21 towards cylinder 13. Hydraulic fluid will then be forced from the reservoir 20, through communicating means 23, and intocylinder 13. Since hydraulic fluid is essentially incompressible, piston 12 will be forced downward; and since piston 12 comprises the majority of the mass, the centrifugal force will be re duced correspondingly.

If the centrifugal force is to be increased, knob 27 will be pulled, causing control rod 25 to retract plunger 21 with a corresponding decrease in pressure of the hydraulic fluid in the fluid reservoir 20 Channel 23 will communicate the reduction in pressure to the hydraulic fluid stored in cylinder 13. The reduction in pressure will cause biasing spring 15 (along with the centrifugal force on piston 12) to force piston 12 away from the axis of shaft causing the hydraulic fluid confined within cylinder 13 to travel down communicating means 23 to hydraulic reservoir 20. Piston 12 will continue to travel until the pressure between the hydraulic fluid on the one side of piston 12 equals the spring bias on the other side of piston 12. Rotation of shaft 10a will not however increase the problem of hydraulic fluid leakage that has heretofore beset this form of centrifugal force control. Plunger 21 is not stationary but is rotating at the speed of shaft 10a, thus O ring 22 is not subjected to Wear other than the axial movement of plunger 21. Since control rod 25 is stationary with respect to shaft 10a, a suitable means of coupling control rod 25 to plunger 21 is provided through bearings 31. Bearings 31 must be adapted to permit rotation as well as axial movement of plunger 21; ball bearings commonly referred to as thrust bearings are satisfactory for this purpose. It is to be understood however that sleeve bearings may be substituted if a means is provided to retain shaft 25 Within the sleeve bearings when axial thrust is applied thereto.

The vibrator also lends itself quite readily to a counter rotating vibratory system as shown in FIG. 2. This type of vibratory system is widely used where it is desired that the resultant force be confined to an upward and downward direction. To accomplish this purpose shaft 40 and rotating mass 41 are rotated in synchronism in a direction opposite from the direction of shaft 42 and rotating mass 43. Rotation is accomplished by any well known method such as gear The resultant energy from the shaft will then coact to form a resultant force in an upward and downward direction as shown by arrow 44. The theory of counter-rotating vibrators has been very well known for a number of years and is extremely adaptable for the vibratory method of such systems as seismic exploration, earth compacting, etc. In order to provide a uniform centrifugal force to such configuration the control rod 25 (see FIG. 3) for each vibrator can be individually adjusted for each change in speed; however, for ease in operation it is recommended that they be joined together in any well known manner.

Thus, an invention has been disclosed which greatly improves the hydraulically controlled variable centrifugal force feature of mechanical vibrators. This invention also permits the vibrator to operate at much higher speeds than has heretofore been possible with greatly improved reliability.

Although this invention has been described with respect to particular embodiments thereof, it is not to be so limited, as changes and modifications may be made therein which are within the spirit and scope of the-invention as defined by the appended claim.

We claim:

A hydraulically controllable, centrifugal force, mechanical vibrator of the type which includes a rotatable shaft, a piston, a cylindrical portion mounted transversely on said shaft and confining said piston, said piston being hydraulically positioned within said cylindrical portion, the improvement comprising: a hydraulic reservoir in said shaft; plunger means axially slideable in said reservoir; plunger control means axially movably and rotatably connected to said plunger means; means for rotating said plunger means with said shaft thereby providing rotary movement of said plunger means independently of said plunger control means; means forming a hydraulic fluid passageway between said reservoir and said cylindrical portion; and, a body of hydraulic fluid in said passageway, said reservoir and said cylindrical portion whereby said piston is moved in response to reciprocal movement of said plunger and plunger control means.

References Cited in the file of this patent UNITED STATES PATENTS 949,872 Abate Feb. 22, 1910 1,939,788 Olson Dec. 19, 1933 2,852,162 Nauta Sept. 16, 1958 FOREIGN PATENTS 23,928 Great Britain Nov. 5, 1904 769,547 Great Britain Mar. 6, 1957 

